active crossover suggestions for biamping?

Junior Member

I dont know if my lingo is even correct, but I am looking to biamp my b&w cdm-1se bookshelf speakers. I need something to set up a band pass filter from 58Hz-4kHz and then a high pass filter at 4kHz for the tweeter. I may or may not want the flexibity to tri-amp in the future (likely determined by cost). Any other options to do this? Im familiar with the passive Harrison Labs filters (RCA style) but wanted to explore other options. Thanks!

Junior Member

There are DSPs, which are digital chips dedicated to running the math to implement a crossover filter, or there are electronic implementations in the analog realm using opamps and whatnot. Most of the world uses DSP, as it is much more flexible. It does imply adding a few more A/D and D/A conversions, depending how you feed them. Crossover use is so boring and routine in DSP that the advertising copy usually barely mentions it, but it's there.

@ICTWoody mentioned MiniDSP, or the Hypex DLCP (which integrates nicely with their amps), or in the "pro" realm, there are "loudspeaker management systems" like the dbx DriveRack Venu360 or BSS MiniDrive or Ashly Protea.

If you want to triamp, you'll need 6 output channels, so the MiniDSP 4X10 HD is probably a good starting point to consider. I run an older MiniDSP Balanced unit; it's a bit electrically noisy and I'm looking to replace it. Newer stuff from them is better, apparently.

Junior Member

Thanks (if you dug that out just for a pic, triple thanks). I need to read up on DSP as it appears to be the direction things are headed in this hobby, offers a lot of flexibility, and is upgradable(“future proof”). Having said that, Im also wondering if there is a simpler version of the units posted in the picture that just has output level and crossover frequency for each of the channels? Correct me, but I dont see a need for any of the other buttons/knobs (is the delay to get them to behave like KEF LS-50s where the tweeter is positioned in the middle of the woofer?) I dont think it is but rather for when youve got multiple speaker sets at larger shows or for maybe HT applications. Do you recommend this feature? I dont think I need it or want it(simpler is better, less circuitry yadada). I plan to set things up proper in the first place so I wouldnt be using it to correct for L/R differences in arrival time to ears. Thanks.

If you're leaning towards the active-analog-circuit approach, you might consider something like the XKITZ devices. I've not heard them, but they appear to be responsibly engineered. Would need to be put in a box and fed with 12 VDC power, an easy project.

For your desired 60Hz-4KHz band pass, you'd want the 3way unit, and not use the lowest freq band. (I'm cheap and cheerful, so I'd run a 2-way all the way down, or maybe use the 3rd band up top)

IMO, You probably don't need time delay; you are correct about the primary use being in larger venues. Folks with duplex speakers like tannoys or big altec horns use it because the HF coil is several inches behind the LF voice coil, and that's a few milliseconds difference. I'd speculate that in a DSP implementation, delay is probably "free", in that it's probably easy to buffer some of the signal in memory for a few ticks before dumping everything to the outputs. Analog? not so much. Coils, capacitors, phase-shift challenges.. etc.

Senior Member

There are DSPs, which are digital chips dedicated to running the math to implement a crossover filter, or there are electronic implementations in the analog realm using opamps and whatnot. Most of the world uses DSP, as it is much more flexible. It does imply adding a few more A/D and D/A conversions, depending how you feed them. Crossover use is so boring and routine in DSP that the advertising copy usually barely mentions it, but it's there.

@ICTWoody mentioned MiniDSP, or the Hypex DLCP (which integrates nicely with their amps), or in the "pro" realm, there are "loudspeaker management systems" like the dbx DriveRack Venu360 or BSS MiniDrive or Ashly Protea.

If you want to triamp, you'll need 6 output channels, so the MiniDSP 4X10 HD is probably a good starting point to consider. I run an older MiniDSP Balanced unit; it's a bit electrically noisy and I'm looking to replace it. Newer stuff from them is better, apparently.

Señor Member

I think anyone starting down this path today would do well to start with DSP.
That said, I think that the past through present have clearly demonstrated that there's nothing less 'future proof' than "digital technology".

Senior Member

I think anyone starting down this path today would do well to start with DSP.
That said, I think that the past through present have clearly demonstrated that there's nothing less 'future proof' than "digital technology".